1. Field of the Invention
The present invention relates to the field of display technology, and more particularly, to a brightness enhancement film, a backlight module and a display apparatus.
2. Description of the Related Art
In a flat panel display, a LCD panel is a device which itself does not emit light. Instead, it uses a backlight unit to emit light. The backlight unit comprises: a support frame for fixing purpose; a reflecting sheet mounted on the bottom surface of the support frame for reflecting light toward the LCD panel; a light guidance plate provided on the reflecting sheet for guiding light; a dissipation sheet provided on the light guidance plate for homogenizing light; a light source provided between the light guidance plate and a side wall of a receiving space of the support frame or disposed below the dissipation sheet for generating light; a prismatic lens provided on the dissipation sheet for concentrating light; a protection film for protecting the dissipation sheet and the prismatic lens; and other optical films or the like.
The microstructure of the prismatic lens used in the backlight source for a LCD panel has a triangle cross section. Typically, a prismatic lens is provided in a longitudinal direction and another prismatic lens is provided in a transversal direction to realize light concentration both in a horizontal direction and in a vertical direction. However, since two prismatic lenses are used, the thickness of the backlight unit and the number of used components are increased. On the other hand, because the microstructure of the prismatic lens has a triangle cross section, the visual angle is relatively narrow.
Instead of the above prismatic lenses, it is proposed a microlens structure for a brightness enhancement film, which, compared with the above prismatic lenses, has a better visual angle effect, but has a relatively poor optical gain effect. FIG. 7 shows a schematic view of a bottom surface structure of the microlens structure for a brightness enhancement film in contact with a substrate in the prior art. As shown in FIG. 7, the microlens structure for the brightness enhancement film is made up of circular microlenses 30. For such circular microlenses 30 in the prior art, light, when passing through spaces 40 between the respective circular microlenses 30, is not concentrated, thus the light focusing effect is abated.